The home cultivation of potatoes offers a rewarding harvest that begins not with a traditional seed, but with a piece of the potato itself. This process relies on vegetative propagation, where a section of the tuber, known as a “seed potato,” is planted to grow a genetically identical plant. This method is the standard practice for growing the vast majority of potato varieties. Success starts long before planting, focusing on the careful preparation of these specialized seed pieces.
Preparing the Seed Potatoes
The first step in growing potatoes is selecting healthy, certified seed potatoes, which are guaranteed to be disease-free and untreated. Avoid planting potatoes purchased from grocery stores, as these are often treated with sprout inhibitors like Chlorpropham (CIPC) to extend shelf life, preventing reliable sprouting. Once acquired, the seed potatoes should undergo “chitting,” or pre-sprouting, approximately six weeks before planting. This involves placing the tubers in a cool, bright, but frost-free location, such as a garage or windowsill, where temperatures hover around 50°F (10°C).
Exposure to light encourages short, sturdy, dark-colored sprouts from the potato’s “eyes,” ensuring quicker emergence and a more robust plant. Larger seed potatoes can be cut into smaller pieces, or “sets,” to maximize the number of plants. Each set should weigh between 1.5 and 2 ounces and contain at least one or two viable eyes.
After cutting, the pieces must be allowed to “cure” for two to three days in a dry, airy place away from direct sun. This curing period allows the cut surfaces to form a protective callus, which reduces the risk of rot or fungal infection once planted. Planting whole, smaller tubers is a viable alternative, especially if they are about the size of a chicken egg.
Choosing the Planting Environment
Potatoes perform best in a site that receives a minimum of six to eight hours of direct sunlight each day. The physical environment of the soil is equally important for successful tuber development. The ideal medium is a loose, well-draining loamy or sandy loam soil rich in organic matter, as compacted soil can lead to misshapen tubers.
A slightly acidic soil pH, ideally ranging from 5.5 to 7.0, is preferred. Maintaining a pH below 7.0 prevents common scab, a bacterial disease that causes rough lesions on the tubers. Planting should commence once the threat of heavy frost has passed and the soil temperature consistently registers above 40°F (4.5°C). The optimal range for fast growth is between 45°F and 55°F (7°C-13°C). Potatoes can be successfully grown in traditional trenches, raised garden beds, or large containers.
Technique for Planting and Hilling
Planting begins by digging a trench or individual holes four to six inches deep. Seed potato pieces are placed in the trench with the cut side down and the chitted eyes pointing upward. Spacing the seed pieces 10 to 12 inches apart in the row allows adequate room for the plants to develop their root systems and tubers.
The rows themselves should be spaced at least two to three feet apart to provide enough soil for hilling. Hilling is the repeated act of drawing soil or organic material up and around the stems of the growing potato plants. This process must begin when the stems reach approximately six to ten inches in height.
The purpose of hilling is twofold: to increase yield and prevent toxicity. Potatoes form on underground stems (stolons), so covering the stem encourages more sites for tuber formation. Hilling also shades the developing tubers, preventing exposure to sunlight, which triggers the production of the toxic alkaloid solanine. This action is repeated every few weeks, burying the stem until only the top leaves are exposed, eventually creating a hill 12 to 15 inches high.
Ongoing Care and Harvesting
Consistent moisture is necessary throughout the growing season, particularly when the plants begin to flower, signaling the start of tuber formation and bulking stages. Potatoes require one to two inches of water per week during this peak growth period. Inconsistent watering, such as alternating between dry and saturated soil, can cause disorders like hollow heart or growth cracks.
Gardeners should monitor for common issues such as the Colorado potato beetle, which defoliates the plants, and late blight, a fungal disease. Selecting certified seed potatoes and practicing crop rotation help minimize disease risk. For harvesting, there are two distinct stages: “new potatoes” and “storage potatoes.”
New potatoes are small, thin-skinned, and ready for harvest two to three weeks after the plants begin to flower. These can be carefully dug from the side of the hill, leaving the main plant to continue growing. For a long-term storage crop, the plant must be allowed to reach full maturity, which is indicated when the entire foliage yellows and completely dies back. Watering should be stopped one to two weeks before harvest to allow the tuber skins to harden. Once dug, mature potatoes benefit from a curing period of seven to ten days in a dark, humid environment (45°F to 60°F) to heal minor scrapes, extending their storage life.